An Epizootic of Mycoplasma Ovipneumoniae Infection in Captive Dall's Sheep (Ovis Dalli Dalli)

Abstract

In late spring of 1986, 10 of 23 Dall's sheep (Ovis dalli dalli) at the Metropolitan Toronto Zoo were moved to a new exhibit, where all developed severe respiratory signs refractory to anthelmintic and antibiotic therapy. In July, two animals died with chronic active bronch-pneumonia, and a third was euthanized because of pneumonia several months later. Bacteria were not isolated from the lungs of the first, steptococci and Pasteurella hemolytica were isolated from the other two, respectively; Mycoplasma ovipneumoniae was isolated from both. Pulmonary lesions in all three sheep were consistent with Mycoplasma sp. infection. Nasal swabs of the remaining animals yielded no consistent bacterial isolates; however, four of eight sheep were positive for M. ovipneumoniae. Viral cultures yielded an as yet unidentified herpesvirus. Sheep in the original and new herds had no serologic titers to parainfluenza-3, equine viral rhinopneumonitis, or infectious bovine rhinotracheitis, and had variable titers against bovine respiratory syncytial virus. No titers against M. ovipneumoniae were present in 13 sheep still in the original exhibit, but titers varied from 1:32 to 1:256 in eight pneumonic sheep. Sera taken from three sheep before or early in the outbreak were all negative for antibody to M. ovipneumoniae. Two of the affected Dall's sheep had been in contact with domestic sheep in the winter of 1985-1986, and M. ovipneumoniae was subsequently cultured from the domestic flock. Exposure to a new pathogen, and environmental and social stress in a new exhibit may have resulted in this severe disease in Dall's sheep.

Mycoplasma ovipneumoniae - A Primary Cause of Severe Pneumonia Epizootics in the Norwegian Muskox (Ovibos moschatus) Population

“…In some other ovine species, M. ovipneumoniae has been associated with severe fatal pneumonia epidemics following contact with domestic sheep. The first report was given for captive Dall's sheep ( Ovis dalli ) in Canada [20] and more recently, M. ovipneumoniae was identified as a primary cause of pneumonia epidemics in free-ranging bighorn sheep ( Ovis canadensis ); a devastating disease that has been recognized in bighorn populations in North America for centuries [21] – [23].…”

Association of Mycoplasma ovipneumoniae Infection with Population-Limiting Respiratory Disease in Free-Ranging Rocky Mountain Bighorn Sheep ( Ovis canadensis canadensis )

“…In bighorn sheep populations outside of Hells Canyon, the association is at the population level based on serologic data obtained from adult bighorn sheep only. A previous study provided strong evidence of a role for M. ovipneumoniae in a pneumonia outbreak in a captive population of a closely related sheep species (Dall's sheep [Ovis dalli]), and the results of that study provided a valuable guide for this investigation (4).…”

“…Indirect hemagglutination was performed as described elsewhere (4,8). Antigen was prepared using Mycoplasma ovipneumoniae strain 06OR03, grown in Mycoplasma broth (Hardy Diagnostics; 37°C, 5% CO 2 , 5 days).…”

Mycoplasmas of Goats and Sheep

“…11,16,102,103 Later studies have suggested that M. ovipneumoniae and Pasteurella hemolytica biotype A serotypes act synergistically to produce a chronic disease (atypical pneumonia) principally affecting lambs up to 12 months of age. 58 Mortality rarely exceeds 10%, 59 even under experimental conditions, but considerable economic loss due to unthriftiness can occur.…”